package cn.maihe.elg.operation.utils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.lang.reflect.Method;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.AccessController;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.PrivilegedAction;

/**
 * <p>Title: </p>
 * <p>Description:  </p>
 * @version 1.0
 */
public class MD5FileUtil {
    private static final Logger logger = LoggerFactory
            .getLogger(MD5FileUtil.class);
    protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6',
            '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
    protected static MessageDigest messagedigest = null;
    static {
        try {
            messagedigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            logger.error("MD5FileUtil messagedigest初始化失败", e);
        }
    }

    public static String getFileMD5(MultipartFile file) throws IOException {
            byte[] uploadBytes = file.getBytes();
            messagedigest.update(uploadBytes);
        String md5 = bufferToHex(messagedigest.digest());
        return md5;
    }

    public static String getFileMD5String(File file) throws IOException {
        FileInputStream in = null;
        FileChannel ch = null;
        try {
            in = new FileInputStream(file);
            ch = in.getChannel();
            MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0,
                    file.length());
            messagedigest.update(byteBuffer);
            String md5 = bufferToHex(messagedigest.digest());
            //删除句柄，否则无法关闭流
            clean(byteBuffer);
            return md5;
        } finally {
            if (in != null) {
                in.close();
            }
            if (ch != null) {
                ch.close();
            }
        }
    }

    public static void clean(final Object buffer) {
        AccessController.doPrivileged(new PrivilegedAction() {
            public Object run() {
                try {
                    Method getCleanerMethod = buffer.getClass().getMethod("cleaner",new Class[0]);
                    getCleanerMethod.setAccessible(true);
                    sun.misc.Cleaner cleaner =(sun.misc.Cleaner)getCleanerMethod.invoke(buffer,new Object[0]);
                    cleaner.clean();
                } catch(Exception e) {
                    e.printStackTrace();
                }
                return null;
            }
        });
    }

    public static String getMD5String(String s) {
        return getMD5String(s.getBytes());
    }

    public static String getMD5String(byte[] bytes) {
        messagedigest.update(bytes);
        return bufferToHex(messagedigest.digest());
    }

    private static String bufferToHex(byte bytes[]) {
        return bufferToHex(bytes, 0, bytes.length);
    }

    private static String bufferToHex(byte bytes[], int m, int n) {
        StringBuffer stringbuffer = new StringBuffer(2 * n);
        int k = m + n;
        for (int l = m; l < k; l++) {
            appendHexPair(bytes[l], stringbuffer);
        }
        return stringbuffer.toString();
    }

    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
        char c0 = hexDigits[(bt & 0xf0) >> 4];
        char c1 = hexDigits[bt & 0xf];
        stringbuffer.append(c0);
        stringbuffer.append(c1);
    }

    public static boolean checkPassword(String password, String md5PwdStr) {
        String s = getMD5String(password);
        return s.equals(md5PwdStr);
    }

    public static void main(String[] args) throws IOException {


    }

}
